Re: emit_event warning in GnomeCanvas

[Owen Taylor <otaylor redhat com>]

jacob berkman <jacob ximian com> writes:

> On Thu, 2001-12-06 at 17:30, Darin Adler wrote:
> > When I click on the background of the icon view in Nautilus, I get a warning
> > from emit_event. The warning is a bit cryptic because it just says
> > "emit_event is about to return FALSE". I think it has something to do with
> > canvas grab, but I don't know what Nautilus is doing wrong to cause the
> > warning to be triggered.
> > 
> > The big problem is that Nautilus runs in a mode where warnings drop into the
> > debugger, and this causes me to drop into the debugger with the pointer
> > grabbed. Then I have to clobber X with Ctrl-Alt-Backspace.
> 
> i have used a patch to gtk 1 which disables the calls to XGrabPointer
> and XUnGrabPointer when an environment variable is set, and found it to
> be very helpful in these cases.
> 
> owen, does this sound like something you'd be willing to put into gtk
> 2.2?

Hmmm, I'm very much a fan of debugging with a second machine for debugging,
though I know not everybody has that option all the time. (I tended
to debug on a VT and switch from X before, now if I don't have a second
machine, I'll use Xnest)

I don't really like disabling pointer grabs because it causes all sorts
of invariants that widgets can expect not to hold true. I suppose
if code can survive without pointer grabs then it should work OK with
them, but I can imagine all sorts of checks for "impossible" cases being
added. 

Qt takes the environment variable idea one further and detects if you
are running under gdb and disables pointer grabs unless you pass a special
option; sort of neat, though perhaps a little overfancy.

Anyways, I don't have any fundemental objection, though I don't want patches
that "fix" things that break run like this. I'd even be willing to take
a patch for 2.0, in fact. (It probably should be done as a debug flag -
GDK_DEBUG=nograb but people tend to have GTK+ compiled without --enable-debug...)

Regards,
                                        Owen